Theoretical analysis of water coverage on MgO(001) surfaces with defects and without F, V and P type vacancies

Semi-empirical (PM3) as well as B3LYP/6-31G* and B3PW91/6-31G* calculations have been performed on large cluster models, (MgO)(16), in order to study the effects of the adsorption of water coverage on defect free and with F, V, and P centers vacancies on MgO(001) surfaces. In order to cross-check our results with more accurate methods we show that our formation energies are in agreement with DFT calculations. The geometric parameters of adsorbed water molecules have been optimized in order to analyze total and binding energies, preferential sites of interaction, Mulliken atomic population and charge redistribution as well as HOMO and energy gap. The acidic-basic characteristics effects of the low and high coverage on energy gaps and SCF orbital energy, values have also been investigated. Our calculations suggest chemically more active surfaces when vacancies are present whereas F and P type vacancies promote better conditions for the water coverage process yielding more adsorbed water molecules. (C) 2003 Published by Elsevier B.V.